This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The incidence of colon cancer increases with age, and this may be related to altered metabolism and disposition of carcinogens. One such carcinogen implicated in colon cancer is the heterocyclic amine found in well done meat, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ). The purpose of these studies was to determine whether the disposition and metabolism of IQ changes with age, comparing young (3-month) and old (22- to 24-month) male F344 rats. Animals were treated with vehicle or beta-naphthoflavone (BNF), an inducer of drug-metabolizing cytochromes P450. Disposition and metabolism of IQ were determined after i.p. injection of radiolabeled IQ.